Characterization magnetic measurements

The complexes /uo[IrL3X(OH2)], HL = phthalimide, X = bpy, phen, have been prepared and characterized by IR and UV-vis spectroscopy, electronic conductance and magnetic measurements.117... 

Chemically the iron complex 18 is reduced by K/Na alloy in THF to give a green solution of the salt 57. The d7 anion in 57 has been characterized by its ESR spectrum in frozen solution (62). Similarly, on treatment with sodium amalgam, the cobalt complexes 7 and 13 yield dark brownish-red solutions of 58 and 59, respectively. A surprisingly robust PPh4+ salt 60 (mp 158-159°C) could be isolated. Solution and solid state magnetic measurements confirm the presence of two unpaired electrons in these 20-e species as in NiCp2 (60). 

The usual techniques for the determination of particle sizes of catalysts are electron microscopy, chemisorption, XRD line broadening or profile analysis and magnetic measurements. The advantage of using Mossbauer spectroscopy for this purpose is that one simultaneously characterizes the state of the catalyst. As the state of supported iron catalysts depends often on subtleties in the reduction, the simultaneous determination of particle size and degree of reduction as in the studies of Fig. 5.10 is an important advantage of Mossbauer spectroscopy. 

These derivatives are soluble in an acetone/water mixture with their p i values similar to that of PIDAA. The phenylene analogs are similar to EDTA except that the two nitrogens are bridged by aromatic rings. These derivatives are soluble in acetone/water. They were characterized by measuring their H- and C-nuclear magnetic resonance (NMR) spectra and Fourier transform infrared (FTTR) spectra. All the PIDAA derivatives showed a peak near 53 ppm for the methylene carbons in carbon NMR spectra. The methylene carbon resonance appears around 44 ppm in the NPG derivative. Thus offers an easier way to characterize these materials. The FTNMR data are listed in Table 1 below. 

MeOpyNO. 4-ClpyNO, or 4-N02pyN0) and [FeL ](C104)2 (L = 4-picoline. V-oxide. 4-MeOpyNO, 4-ClpyNO, 4-N02pyN0, 4-CNpyNO, or 3-CNpyNO) have been prepared, and have been characterized by magnetic measurements and i.r. and electronic spectroscopy. ... 

In addition to X-ray and neutron-diffraction structural characterization, the physical properties of iron oxides have been studied by a wide variety of techniques. Most common are conventional transport, optical, dielectric, calorimetric and magnetic measurements. In addition, NMR and Mossbauer are widely used. 

Along this line, the limitations of the technique used must be recognized. Some measure predominantly bulk properties, e.g., X-ray diffraction and magnetic susceptibility whereas, others are sensitive to surface composition, e.g., adsorption and ESCA. For example, in one reported study only cobalt in tetrahedral coordination was found on a catalyst by diffuse reflection spectroscopy, but magnetic measurements revealed that octahedral cobalt must also be present (10). Thus, it is dangerous to rely on any one method to characterize these catalysts. 

One of the earliest studies on the CoMo/Al catalyst was done by Richardson (59) employing magnetic measurements. He characterized the oxidized catalyst in terms of bulk compounds, which is clearly incorrect in view of later work. On this basis, and the known sulfidibility of the compounds, he deduced the active catalyst consisted of an MoS2 phase containing Co of an unknown stoichiometry. 

The complexes obtained were characterized by x-ray diffraction and magnetic measurements. Iron-57 Mossbauer spectroscopy data for Fe(SQ)3 complexes are consistent with the iron ion being described as high-spin iron(III) [227,228]. 

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